The hacking of wallets

Good day! Please tell me how this is possible? Hacked wallets to which EMB tokens were transferred. They were withdrawn from me and from another 7 people in one hour after the EMB tokens arrived on the wallets. What to do in this case? Was there any mistake in the smart contract?

I did not buy wallets with OTC. My private key was known only to me and the key was on the USB drive for three years.

The address from which the EMB was stolen


The address of the intruder as I understand it he stole the EMB of 5 more people